System information

And now, without further ado, let’s take a look at the modules, grouped by module
type.
Applications
Dialplan applications are used in extensions.conf to define the various actions that can
be applied to a call. The Dial() application, for example, is responsible for making
outgoing connections to external resources and is arguably the most important dialplan
application. The available applications are listed in Table 2-1.
Table 2-1. Dialplan applications
Name Purpose Popularity/Status
app_adsiprog Loads Analog Display Services Interface (ADSI) scripts into
compatible analog phones
Insignificant
app_alarmreceiver Supports receipt of reports from alarm equipment Insignificant
app_amd Detects answering machines Unreliable
app_authenticate Compares dual-tone multi-frequency (DTMF) input against
a provided string (password)
Useful
app_cdr Writes ad hoc record to CDR Useful
app_celgenuserevent Generates user-defined events for CEL New
app_chanisavail Checks the status of a channel Unreliable
app_channelredirect Forces another channel into a different part of the
dialplan
Useful
app_chanspy Allows a channel to listen to audio on another channel Useful
app_confbridge Provides conferencing (new version) New—not fully featured yet
app_controlplayback Plays back a prompt and offers fast forward and rewind
functions
Useful
app_dahdibarge Allows barging in on a DAHDI channel Deprecated—see
app_chanspy
app_dahdiras Creates a RAS server over a DAHDI channel (no modem em-
ulation)
Insignificant
app_db Used to add/change/delete records in Asterisk’s built-in
Berkeley database
Deprecated—see func_db
app_dial Used to connect channels together (i.e., make phone calls) Essential
app_dictate Plays back a recording and offers start/stop functions Useful
app_directed_pickup Answers a call for another extension Useful
app_directory Presents the list of names from voicemail.conf Useful
app_disa Provides dialtone and accepts DTMF input Useful
a
app_dumpchan Dumps channel variables to Asterisk command-line
interface (CLI)
Useful
12 | Chapter 2: Asterisk Architecture